The present invention relates to a method for generating hydrogen through electrolysis of water or aqueous solutions.
Hydrogen is of increasing importance as a basic material in the chemical industry, for example, hydrogen is utilized as a raw material in the production of plastics, and as an energy carrier of the future, as either a complete or partial replacement for electric power.
At present, hydrogen is primarily (about 78%) produced by petrochemical processes which are based on fossil fuels such as petroleum and coal as primary energy carriers. The generation of hydrogen from such energy carriers is, however, relatively expensive, and furthermore, the petroleum reserves, i.e., the availability of hydrocarbons, are limited. There have, accordingly, been numerous attempts to make the production of hydrogen independent of hydrocarbons.
In particular, the electrolysis of water, i.e., the dissociation of water through the supply of electric energy, suggests itself as a means for the production of hydrogen. Although presently considered as technically mature, this method, in which oxygen is formed in addition to hydrogen, needs improvement in its energy efficiency, which presently is only between about 45 to 65%.
In the electrolysis of water, it is a further disadvantage that the entire energy to be spent must be supplied in the form of valuable electric energy. Many proposals have, therefore, been made to split the overall reaction of water dissociation into individual steps in a manner such that a purely thermal cycle results (see, for example, British Patents Nos. 1,408,254 and 1,408,255, as well as U.S. Pat. Nos. 3,932,599 and 3,995,012). Such thermochemical cyclic processes, however, still present difficulties regarding the feasibility of the individual process steps, and in addition, they suffer from still unsolved problems of material separation and as yet unresolved material problems.